Subsequent to our studies and reports of the prevalence of hyperactivity among children and the prevalence of various treatment regimens for children considered to be hyperactive, the objective of our research has been to conduct a longitudinal study of the life histories of hyperactive and control subjects through high school. The research design to achieve this objective is guided by a structural model which hypothesizes an interaction between environmental, medical and subject factors which, in turn, affect the identification, treatment and life history outcomes for hyperactive children. We have defined each of these domains of interest, and within each domain we have developed a number of reliable and valid measures. A major goal of our work is to substantiate and modify, where appropriate, our structural model, and to verify our theoretical scheme with statistical evidence. Based on our findings thus far, one must account for constitutional, environmental, and individual difference factors in explaining the identification of a child as hyperactive. Moreover, it is apparent that there is limited evidence for a medical condition accounting for childhood hyperactivity. Rather, our evidence is beginning to show clearly that behavioral factors, rather than physiological or neurological factors, account for a child being considered and treated as hyperactive. Therefore, our life history studies assume even greater importance as we examine the unique and joint contribution of individual difference variables and home and school environmental factors, as well as medical evidence, to being identified and treated as hyperactive. Our research shows that these factors affect also the length of time a child is considered to be hyperactive, the types of treatments he or she undergoes, as well as eventual adolescent outcomes.